JP5091479B2 - Carbon dioxide recovery - Google Patents

Description

  The present invention relates to a method and system for recovering carbon dioxide from carbon dioxide, co-solvents and contaminated streams from one or more processing means operated discontinuously.

Carbon dioxide (CO ₂ ) based systems are gaining importance in the electronics industry, particularly in the manufacture of semiconductor components. CO ₂ based systems can be utilized for many tasks including chemical fluid deposition, photoresist deposition, and photoresist development and removal. For example, supercritical CO ₂ can be used to remove photoresist (ie, contaminants) from a semiconductor wafer.

  Wafers with contaminants on the surface are placed in several cleaning chambers containing processing means. Carbon dioxide and one or more co-solvents such as water or acetone are injected into the chamber and the wafer is cleaned. During at least part of this cleaning process, the chamber temperature and pressure meet or exceed the carbon dioxide supercritical temperature and pressure. The carbon dioxide, co-solvent, and contaminants are then evacuated from the chamber so that the chamber pressure returns to the atmosphere. In order to minimize the loss of carbon dioxide and co-solvent when the processing means is depressurized, a valve that separates the stream containing carbon dioxide, co-solvent and contaminants from the processing means is located as close to the processing means as possible. Is done. The clean wafer is then removed from the chamber.

Typically, streams containing carbon dioxide, co-solvents and contaminants exhausted from the processing means may need to be cleaned before venting to the atmosphere as these materials can be harmful. Furthermore, in order to minimize the consumption and overall cost of CO _2, it is often desirable to recycle to purify at least part of the carbon dioxide contained in the exhaust stream.

  Several carbon dioxide capture systems have been proposed in the related art. For example, U.S. Pat. Nos. 4,349,415 and 4,877,530 disclose a method in which the carbon dioxide device (i.e., the processing means) operates at a constant pressure above the triple point of carbon dioxide. . In these disclosures, carbon dioxide is used in a continuous extractor to remove the extract from the raffinate, forming an extract rich stream and a raffinate rich stream. The extract-rich stream contains the majority of carbon dioxide and continuously passes through purification and recycling means. The raffinate rich stream also contains a small amount of carbon dioxide and is sent to the phase separator. The phase separator produces a liquid stream rich in raffinate content and a vapor stream rich in carbon dioxide. The vapor stream rich in carbon dioxide is sent to a holding tank to attenuate any fluctuations in the flow, and then compressed and recycled.

  Since the processes described in US Pat. Nos. 4,349,415 and 4,877,530 are operated continuously, the pressure in the extractor never drops to atmospheric levels. Thus, the phase separator can be operated at any pressure that accommodates downstream processes. The phase separator is preferably operated at a pressure above atmospheric pressure so that the vapor stream rich in carbon dioxide can be transferred to other devices such as a holding tank without first being compressed. Also, operating the phase separator at a pressure above atmospheric pressure will reduce the required holding tank capacity and compression force.

  If the processing equipment (ie, the extractor) described in US Pat. Nos. 4,349,415 and 4,877,530 is operated batchwise as described in other related arts, Several problems will occur. It will be necessary to reduce the pressure of the processing equipment to atmospheric levels during its operation. This will result in the need to operate the separator at atmospheric pressure. Thus, compression will be required to move the vapor stream rich in carbon dioxide to other devices such as holding tanks. Instead, the separator could be operated at pressures above atmospheric pressure. This requires that any steam below the separator operating pressure remaining in the extractor be transported for discharge as an exhaust stream. This exhaust stream will exist as a multiphase stream such as some combination of vapor, liquid and solid. This movement of the multiphase flow to be discharged is very difficult and will adversely affect downstream equipment due to, for example, solid and liquid deposition. The effluent stream can be compressed so that it can be sent to a separator. However, this requires the use of additional compression devices, resulting in a significant cost increase. In addition, the carbon dioxide devices disclosed in these patents are continuous and are not involved in maintaining a constant flow to downstream processes.

  International Publication No. WO 02/085528 describes a method of using a single separation vessel, with a wide range of pressures to improve and recycle the quality of liquid carbon dioxide or supercritical carbon dioxide leaving the carbon dioxide device. Driven. The vessel is called an expansion-condenser and is operated in batch mode. The liquid leaving the carbon dioxide device is pumped to a high pressure liquid holding tank. The liquid removed from the holding tank is sent to an expansion-condenser that is physically located in the holding tank.

  When the level of liquid in the expansion-condenser reaches the desired value, the supply is stopped. The pressure on the expansion-condenser is then gradually reduced to initially contain a high level of co-solvents and contaminants, but when the expansion-condenser pressure is reduced, a co-solvent and contaminant-free vapor stream is formed. Is done. When the co-solvent and contaminant levels for the vapor stream are reduced to an acceptable level, the vapor stream is released and recycled.

  Since the expansion-condenser is operated in a batch mode, no continuous vapor stream is generated, which adversely affects downstream equipment. Other adverse effects of this phase separation system can be costly due to the use of special systems and the difficulty in designing compression / pump devices, especially when corrosive substances are present. Finally, it is difficult to pump carbon dioxide, co-solvent and pollutant containing streams leaving the carbon dioxide device to the holding tank using a pump. This is because when the carbon dioxide device is depressurized, this flow changes from the liquid phase to the multiphase to the gas phase. Further, as the expansion-condenser pressure approaches atmospheric pressure, the carbon dioxide vapor leaving the phase separator further requires a compression means that is resistant to the corrosive elements trapped in the compression means.

  Finally, the related art describes the use of multiphase separators to separate carbon dioxide from carbon dioxide, co-solvent and contaminant-containing streams leaving the carbon dioxide device. US Patent Application 2001/0050096 describes these methods. In the process described there, the pressure on the carbon dioxide, cosolvent and contaminant-containing stream leaving the processing means is reduced. The resulting intermediate pressure stream is sent to a heated intermediate pressure phase separator to produce a vapor stream rich in carbon dioxide and a liquid stream rich in cosolvents and contaminants. The vapor stream rich in carbon dioxide is filtered and sent to the first condenser, from which substances having a higher vapor pressure than carbon dioxide are discharged. The co-solvent and contaminant rich liquid stream leaving the intermediate pressure phase separator is depressurized to a pressure somewhat above atmospheric pressure and sent to the low pressure separator, where the cosolvent rich vapor stream and the contaminant rich liquid stream. Is generated. The vapor stream rich in co-solvent is sent to a second condenser, where substances that are more volatile than the co-solvent are discharged. The pollutant rich liquid stream leaving the low pressure phase separator is collected for disposal.

  One disadvantage associated with the multiphase separator of US Patent Application 2001/0050096 is that the intermediate phase separator and most of the operations located downstream are designed to operate continuously. To ensure continuous operation, when carbon dioxide, co-solvent and contaminant-containing fluid are not discharged from the processing means, the carbon dioxide bypasses the means and is sent to an intermediate pressure phase separator. The process becomes inefficient because the force used to pressurize the carbon dioxide normally supplied to the treatment means is released by the detour.

  Furthermore, since the intermediate pressure phase separator is operated continuously, the pressure cannot be reduced to near atmospheric. Thus, the pressure of the processing means cannot be reduced to the atmosphere by discharging its contents into this separator. In order to reduce the pressure of the processing means to the atmosphere, the liquid present at a pressure equal to and less than that associated with the intermediate pressure phase separator is discharged into another container independent of all the aforementioned containers. . The container is heated to completely vaporize any material that enters it. The resulting vapor is sent to an exhaust cleaning system. Some co-solvents and contaminants have very low vapor pressures, so this vessel will need to be heated above the atmosphere to fully vaporize its contents. As the vapor leaving this container moves to the exhaust cleaning system, it will be cooled for the heat sink. As a result, these very low vapor pressure materials recondense and accumulate on the process piping, causing the multiphase flow problems described above. These adverse effects are exacerbated when the co-solvent is corrosive.

  An additional disadvantage with this method is that the carbon dioxide rich vapor leaving the intermediate pressure phase separator and finally circulating to the processing means is not low in vapor pressure with respect to the cosolvent / contaminant material. The associated co-solvent / contaminant level is increased. Therefore, the processing means may be contaminated. In addition, if corrosive cosolvents are used, they can damage the compressor or pump that pressurizes the recycled carbon dioxide downstream of the first condenser.

  US Patent Application 2002/0023662 describes a process that uses a multistage distillation column to separate a solvent and contaminant-containing stream leaving an extractor. As described there, the extraction device removes contamination from solid adsorbents such as clay. Supercritical carbon dioxide is listed as a possible solvent. Solvent and contaminant-containing liquid leaving the extractor is sent to a holding tank to eliminate flow rate fluctuations due to batch extraction operations. Liquid is pumped from this holding tank to the first distillation column, producing a first solvent rich stream and a first contaminant rich stream. The first solvent rich stream is recycled to the extractor without further purification. Therefore, a multistage distillation column is required. Distillation columns require continuous feed and a holding tank. Furthermore, since the column is reboiled, a pure liquid solvent must be fed to the top of the column. Since the solvent and contaminant-containing stream is not a pure liquid solvent, some product solvent stream must be condensed and recycled to the column, resulting in inefficiencies.

  The first contaminant rich stream is sent to a second separation distillation column to produce a second solvent rich stream and an essentially pure contaminant stream. A distillation column is necessary because contaminants are the desired product. The solvent rich stream is condensed and recirculated to the first separation means by a pump. An essentially pure contaminated stream is collected and discarded or reused.

  A further disadvantage with this system is that the pressure in the holding tank cannot be reduced to near atmosphere because carbon dioxide does not exist as a liquid near atmospheric pressure. Therefore, the pressure of the extractor cannot be lowered to the atmosphere by discharging its contents into the holding tank. In order to reduce the extractor pressure to the atmosphere, the liquid contained in the extractor at a pressure equal to and less than that for the holding tank is discharged into the second distillation column. This is a major operational problem because the separation of these columns is not good anyway in a discontinuous feed. In addition, if the solvent is supercritical carbon dioxide, the second distillation column will not function well because carbon dioxide cannot exist as a liquid at atmospheric pressure. Carbon dioxide is likely to be present as a solid in the second column, which tends to clog the column.

  A further disadvantage of replacing the first distillation column with a phase separator is that the carbon-rich vapor leaving this phase separator contains high levels of contaminants because the vapor pressure for these materials is not small. Will. Since no further separation means are used, the extractor will be contaminated. Furthermore, if corrosive solvents are used, they can damage the compressor or pump that pressurizes the recycled carbon dioxide. Therefore, the use of a phase separator is not acceptable.

  It is an object of the present invention to provide a method and system for recovering carbon dioxide from a discontinuous carbon dioxide stream released from at least one batch processing means to overcome the disadvantages of the related art.

  Another object of the present invention is to allow the processing means to evacuate to atmospheric pressure.

  It is a further object of the present invention to further move streams containing corrosive, toxic or harmful substances such as acids and bases to a purification and / or exhaust cleaning system.

  It is a further object of the present invention to attenuate process condition fluctuations associated with feeding to further purification systems during operation of the processing means.

  Other objects and aspects of the present invention will become apparent to those skilled in the art upon review of the specification, drawings, and claims appended hereto.

The foregoing objects are met by the system and method of the present invention. According to a first aspect of the present invention, a system for purifying at least one carbon dioxide-containing stream from at least one batch process means is provided. The system
(A) removing at least one contaminated stream comprising at least one carbon dioxide, one or more solvents, and one or more contaminants from at least one batch processing means, and multiphase contamination; Reducing the pressure of each contaminated stream producing the stream;
(B) carrying each multiphase contaminated stream to at least one intermediate pressure separator;
(C) separating the multiphase pollutant stream into an intermediate pressure carbon dioxide rich stream and a pollutant rich stream, mainly in each intermediate pressure separator, mainly comprising a vapor solvent;
(D) switching the transport of the multiphase contaminated stream to a low pressure separator;
(E) separating the multiphase contaminated stream of step (d) into a low pressure carbon dioxide rich stream and a low pressure solvent and contaminant rich stream in a low pressure separator.

  According to another aspect of the invention, a system for purifying at least one carbon dioxide-containing stream from at least one processing means is provided.

The system
(A) supplying one or more first co-solvents and purified carbon dioxide to one or more treatment means to form a first contaminated stream in each treatment means;
(B) conveying each first contaminated stream in multiphase form to at least one first intermediate pressure or low pressure separator to separate the first contaminated stream;
(C) supplying one or more second co-solvents and purified carbon dioxide to the processing means to form a second contaminated stream in the processing means;
(D) conveying each second contaminated stream in multiphase form to at least one second intermediate pressure or low pressure separator and separating the second contaminated stream.

  Objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings. Similar numbers represent the same shape.

  In the present invention, the carbon dioxide containing stream is removed from one or more processing means including one or more processing chambers. The processing means is operated in a discontinuous or batch mode, releasing the pressure in the chamber to atmospheric conditions. The contaminant-containing stream removed from the treatment means is conveyed to one or more pressure vessels where it is separated into a carbon dioxide vapor stream and a liquid contaminant-containing stream. Specifically, the carbon dioxide-containing stream exiting the means can be processed according to the following non-limiting embodiments and recycled back to the processing chamber for further use.

FIG. 1 shows a schematic diagram of a processing system according to one aspect of the present invention. Purified carbon dioxide stream 1 and one or more co-solvents 2 and 3 are conveyed to processing means 10. It will be appreciated that the processing means 10 may include one or more chambers 4, 5 that can be operated independently of each other. The means is operated such that the carbon dioxide stream is near critical, critical, or supercritical for at least part of its operating time. As used herein, the terms critical and supercritical carbon dioxide are those skilled in the art, which are equal to or greater than the supercritical temperature and pressure of CO ₂ , typically 87.8 ° F. and 1085 psia, respectively. It will be readily understood that having a temperature and pressure. Near-critical carbon dioxide is present at temperatures from -49 ° F to 87.8 ° F, and pressures above or equal to 1085 psia. See Superfluids Cleaning and Fundamentals Fundamental Technologies and Applications of John McHandy et al., Noes Publications, Copyright, 1998. In it, carbon dioxide and a co-solvent are combined to perform one of any number of operations including photoresist removal. These cosolvents can be selected over a wide range including water and acetone. Thus, the emissions leaving the processing means 10 are carbon dioxide, co-solvents and contaminants (eg, non-volatile materials such as photoresist).

  Streams 20 and 30 exiting chambers 4 and 5 are initially at the operating pressure of the processing means, respectively. Of course, the operating pressure and temperature depend on the operation being performed. A suitable maximum operating pressure range for the processing means is about 800-5000 psig. A suitable operating temperature range is about −50 to 300 ° F. Streams 20, 30 pass high pressure valves 21, 31 to depressurize the processing chamber to a low pressure, typically 200-800 psig. While not wishing to be bound by any particular theory, in supercritical conditions, the flow exiting the processing chamber may or may not exist as a single phase mixture. However, when the flow exits the processing means and is throttled to low pressure, the flow becomes multiphase. Typically, multiphase flows include vapor, liquid, and solid components. The presence of multiple phases can lead to contamination of piping, instrumentation or process equipment and / or create undesirable flow characteristics (ie clogged or stratified flow). These undesirable flow conditions will damage downstream equipment including exhaust cleaning systems. In addition, the corrosive nature of the multiphase flow will also contribute to adverse effects on downstream equipment. The resulting low pressure carbon dioxide, co-solvent, and contaminants downstream of the high pressure valve because the pressure in the processing chambers 4, 5 of the feed streams 20, 30 exceeds a predetermined value for the pressure on the separator 40. Each of the containing streams 22, 23 is sent to an intermediate pressure separator 40. The predetermined pressure difference is preferably from about 0 to about 50 psig. Most preferably, the predetermined pressure difference is about 2 psig.

  Carbon dioxide, co-solvent, and contaminant-containing streams 20, 30 exiting the processing means 10 utilize an intermediate pressure separator 40, an intermediate pressure carbon dioxide rich vapor stream 42, and an intermediate pressure co-solvent and contaminant. Separated into a rich liquid stream 43. As used herein, the terms vapor flow and liquid flow will readily be understood by those skilled in the art to mean at least 50 weight percent vapor and liquid phases, respectively. Further, it will be appreciated that the pressure separator 40 can be a single phase separator or a multi-stage separator capable of separating a multi-phase flow. An example of a multi-stage separator is a reflux condenser.

  The amount of carbon dioxide released into the contaminant liquid stream 43 can be controlled by heating the intermediate pressure phase separator 40 to a temperature typically in the range of about −100 ° F. to 200 ° F. The operating temperature of the separator is preferably between 32 ° F and 120 ° F. Most preferably, the temperature generated in the separator is between 50 ° F and 120 ° F. Further, the pressure associated with the intermediate phase separator 40 can be sent further to the purification means 80, 83 without the need for the vapor stream 42 rich in intermediate pressure carbon dioxide to compress the vapor stream 42 exiting the intermediate separator 40. Selected as Typically, the intermediate separator 40 is operated at a pressure in the range of about 200-900 psig, more preferably about 250-450 psig.

  The pressure in the processing chambers 4 and 5 decreases when the processing means returns to atmospheric pressure, and therefore the pressure in the feed streams 20 and 30 carried to the intermediate separator 40 decreases. When the pressure difference between streams 20, 30 and intermediate pressure separator 40 reaches a predetermined value (eg, 2 psig), high pressure valves 21, 31 are closed and low pressure valves 24, 34 are open. Low pressure carbon dioxide, co-solvent and contaminant-containing streams 25, 35 are sent to a low pressure separator 50 where a low pressure co-solvent and contaminant rich liquid stream 53 and a low pressure carbon dioxide rich vapor stream 52. Is generated. The low pressure separator 50 is typically operated at approximately atmospheric pressure so that the processing means is fully depressurized. The amount of carbon dioxide released into the contaminant liquid stream 53 can be controlled by heating the low pressure phase separator 50 to a temperature typically in the range of about −100 ° F. to 200 ° F. . The operating temperature of the separator is preferably between 32 ° F and 120 ° F. Most preferably, the operating temperature of the separator is between 50 ° F and 120 ° F. The low pressure co-solvent and contaminant rich liquid stream 53 exiting the low pressure separator 50 is carried to waste, such as a collection drum 63, and the low pressure carbon dioxide rich vapor stream is directed to a series of coalescers 60. Any aerosol that can be carried and trapped in the vapor stream is removed.

  Although this preferred embodiment uses the pressure differential as a basis for carrying the low pressure carbon dioxide, co-solvent and contaminated streams 22, 32 to the intermediate or low pressure separator, other factors can be used. Examples of these alternative factors include pressure, temperature, or flow rate for streams 22, 23, and pressure or temperature for intermediate pressure separators or processing means. The difference between the processing means and the intermediate separator can be calculated using pressure, temperature or flow rate. Alternatively, the pressure reduction time or pressure drop rate or temperature rise rate of the processing means can be used to determine whether to send streams 22, 23 to an intermediate or low pressure separator. All of these calculations are used to determine the appropriate switch point using flow rate, temperature, pressure or time as the measured quantity.

  The aerosol captured by the coalescer 60 can be sent to the waste collection drum 63 and the recovered vapor can be sent to an exhaust cleaning system for further purification.

  An intermediate pressure co-solvent and contaminant rich liquid stream 43 exiting the intermediate pressure separator 40 can be sent to the low pressure separator 50, which passes the contaminant rich vapor stream 43 to a low pressure carbon oxide. Further separation is preferably made into a vapor stream 52 rich in water and a liquid stream 53 rich in low pressure co-solvents and contaminants. A liquid stream 53 rich in low pressure co-solvents and contaminants can be sent to the waste collection drum 63.

  According to one aspect of the invention, the flow rate 44 for the intermediate pressure carbon dioxide rich vapor stream 42 is relatively fixed while the processing means is operated by manipulating process parameters for this flow, such as pressure, temperature or flow rate. Value is maintained. For example, during operation of the processing means, a valve 45 disposed in the vapor stream 42 rich in intermediate pressure carbon dioxide is operated to maintain a constant flow rate reading of the flow measurement device 44 disposed in this flow. be able to. In this way, the pressure in the intermediate pressure vessel 40 will vary, but its output flow rate will be kept constant.

  The intermediate pressure carbon dioxide rich vapor stream 42 exiting the intermediate pressure separator 40 is further purified to remove corrosive and toxic and harmful substances such as acids and bases in the vapor stream for safety to other equipment. Movement can be facilitated. Possible further purification means include reaction, distillation, phase separator, filtration, adsorption, absorption or coalescence. For example, if acid is present, vapor stream 42 can be preheated using heat exchanger 70 and optionally trim heater 72 before conveying vapor stream 42 to reaction means 74. One skilled in the art will appreciate that conventional neutralization means including limestone or alumina beds can be utilized.

The neutralized stream 75 leaving the reactor means 74 passes through the filter 76 to remove particles trapped in the stream. Subsequently, the neutralized stream 75 is conveyed through heat exchanger 70 and cooled to a temperature typically in the range of about 50 ° F to 200 ° F. Then neutralized stream has a CO ₂ different vapor pressure, water, any residual materials such as hydrocarbons and other contaminants can be transported to a further purification unit 80 that would remove. They further purification means, "middle CO ₂ purifier (Central CO ₂ Purifier)" and "recycled supercritical carbon dioxide (Recycle for Supercritical Carbon Dioxide)", Attorney Docket No. 3011.1003-001 and 3011. 004-001, which is incorporated herein by reference in its entirety. As shown in these applications, the second further purification means 80 is a general purpose so as to process the carbon dioxide stream 81 from the other means and then distribute the carbon dioxide stream 82 to the other processing means. There is sex.

  As the carbon dioxide stream 78 is further purified, an operational grade purified carbon dioxide stream 1 is formed and recycled back to the processing means 10. Typically, the purified carbon dioxide stream 1 contains less than 10 ppm impurities, with 1 ppm impurities being most preferred.

  As described above, the processing means 10 is operated batchwise or discontinuously. Therefore, the temperature and pressure of the multiphase flows 20 and 30 vary greatly. Many carbon dioxide purification and recirculation system components, such as distillation columns, heat exchangers, and switched bed adsorption systems, perform very poorly or do not function at all if the flow characteristics are insufficient. Process parameters and configurations for further purification systems can be varied to maintain a constant flow rate in the system. Instead, a bypass stream of operational grade purified carbon dioxide 11 is removed from the recirculation line and conveyed to the intermediate pressure separator 40 to ensure that a vapor stream 42 rich in carbon dioxide is continuously fed to the purification unit. be able to. Optionally, the bypass stream 11 can bypass the intermediate pressure separator 40 and be carried directly to the carbon dioxide rich vapor stream 42.

  A further advantage of bypassing the purified carbon dioxide stream 11 is that it provides a continuous flow rate, thereby preventing the carbon dioxide from stagnating in the supply line of the processing means. The stagnant carbon dioxide can leach out elastomers or other particles to generate contaminants from the process line, which can be concentrated and deposited in the processing means. Also, the diverted liquid carbon dioxide 11 could clean the contaminated line downstream of the processing means when such contamination occurs.

  In practice, the time of operation of the chambers and / or means can be specified to minimize the number of chambers and / or means that discharge contaminated flow.

  In another aspect of the invention, two systems are provided in parallel, and purified carbon dioxide is followed by at least two separate cosolvent streams added to the treatment means. The use of a parallel separation system is advantageous, for example, if the cosolvent is collected and recycled, or if the cosolvents used are not compatible with each other. Referring to FIG. 2, a first co-solvent 2 is added to the treatment means 10 along with the co-solvent and contaminant-free carbon dioxide stream 1. Contaminated streams 20, 30 containing co-solvent 2 therein are conveyed to intermediate pressure separator 40 and / or low pressure separator 50 and processed as described above.

  Subsequently, a second co-solvent 3 is added to the processing means 10 together with the co-solvent and contaminant-free carbon dioxide stream 1.

  The contaminated stream or source stream 20, 30 containing the cosolvent 3 therein is evacuated from the processing means. These streams are conveyed to the second intermediate pressure separator 120 or the second low pressure separator 130. One advantage of this configuration is that the first co-solvent 2 can be collected on the waste collection drum 63 independently of the second co-solvent 3 that would be collected on the second waste collection drum 143. It is. Contaminated streams 20, 30 having co-solvent 2 therein are treated as described above with reference to the first aspect of the invention.

  As shown in FIG. 2, in this embodiment, a contaminant-containing stream 20, 30 having a cosolvent 3 therein exits the treatment means 10. Initially, streams 20, 30 are the operating pressure of the processing means, for example 2000 psig. The contaminant-containing stream is passed through high pressure valves 100, 110 to depressurize the processing means 10.

  The resulting multiphase carbon dioxide, co-solvent and contaminant-containing stream 101, 111 has a second intermediate pressure because the pressure of the source stream 20, 30 in the process chambers 4, 5 exceeds a predetermined pressure for the separator 120. Delivered to separator 120. The predetermined value is preferably about 2 psig.

  Using the second intermediate pressure separator 120, the pollutant-containing stream 20, 30 exiting the processing means 10 is converted to an intermediate pressure carbon dioxide rich vapor stream 122 and an intermediate pressure cosolvent and contaminant rich liquid stream 123. To separate. The intermediate pressure separator 120 can include a heater 121 for delivering energy to the separator. That is, the energy delivered to the separator 120 controls the amount of carbon dioxide that is a loss of the co-solvent and contaminant rich liquid stream 123.

  The pressure associated with the intermediate pressure separator 120 purifies the intermediate pressure carbon dioxide rich vapor stream 122 from the separator 120 by further purification means 80, 83 without compressing the intermediate pressure carbon dioxide rich vapor stream 122. Selected to be able to. A typical pressure for the intermediate pressure separator is 300 psig.

  As the pressure of the contaminant-containing streams 20, 30 decreases, the pressure of the stream at the processing means approaches that in the second intermediate pressure separator 120. When the difference between these values reaches a predetermined value (eg 2 psig), the high pressure valves 100, 110 are closed and the low pressure valves 102, 112 are opened. The resulting lower pressure carbon dioxide, co-solvent, and contaminant-containing streams 103, 113 are conveyed to a second low pressure separator 130.

  Also, the intermediate pressure co-solvent and contaminant rich liquid stream 123 exiting the second intermediate pressure separator 120 is combined with the low pressure carbon dioxide rich vapor stream 132 and the low pressure co-solvent. And can be conveyed to a second low pressure separator 130 for further separation into a contaminant liquid stream 133. The low pressure co-solvent and contaminant rich liquid stream 133 can be conveyed to a waste collection drum 143.

  The low pressure carbon dioxide rich vapor stream 132 can be conveyed to a second series of coalescers 140 to remove the aerosol. The captured aerosol 142 can be discharged to the waste collection drum 143 as well. Vapor leaving the second coalescer 141 is carried to the exhaust cleaning system.

  If desired, the stream 124 for the intermediate pressure carbon dioxide rich vapor stream 122 is relatively fixed by manipulating process parameters for this stream, such as pressure, temperature, or flow rate, while operating the processing means. Can be kept in value. For example, a valve (not shown) disposed in the intermediate pressure carbon dioxide rich vapor stream 122 is operated to maintain a constant flow rate reading of the flow measurement device 124 disposed in this stream. be able to. In this way, the pressure in the intermediate pressure vessel 120 will vary, but its output flow rate will remain relatively constant.

  Further, if desired, a constant flow rate can be maintained by passing some of the purified carbon dioxide around the treatment means 10. The diverted stream 14 can be carried by the stream 12 either to the second intermediate pressure separator 120 or to a downstream point of the intermediate separator 120, and is guaranteed to continuously supply carbon dioxide rich steam 122. The

  The intermediate pressure carbon dioxide rich vapor stream 122 is combined with the carbon dioxide rich stream exiting the first intermediate pressure separator 40 for further pretreatment, and as described above, this stream is further purified by means 83 and the second purification means 83. By passing two further purification means 80, for example, corrosive and toxic harmful substances can be removed. Alternatively, these streams can be combined after passing through their own separate first purification means, but before the second purification means. If desired, the vapor stream 141 leaving the second coalescer 140 can be mixed with the vapor stream 61 leaving the first coalescer.

  Although the invention has been described in detail with reference to specific embodiments thereof, those skilled in the art can make various changes and modifications without departing from the scope of the appended claims. It will be apparent that can be used.

1 is a schematic diagram of a carbon dioxide recovery system according to a first embodiment of the present invention. It is a schematic diagram of the carbon dioxide recovery system by the 2nd Embodiment of this invention.

Claims (2)

A method for purifying at least one carbon dioxide-containing stream from a batch process means comprising:
(A) supplying one or more first co-solvents and purified carbon dioxide to the processing means to form a first contaminated stream in the processing means;
(B) carrying the first contaminated stream in multiphase form to a first intermediate or low pressure separator, wherein the first contaminated stream is a first carbon dioxide rich vapor stream and a first co-solvent; When a step of separating the liquid stream enriched in the first contaminants, firstly said first contaminant stream carries the to the first intermediate pressure separator wherein the first intermediate pressure separated from the batch type processing means When the first pressure difference with the vessel reaches a first predetermined value, the first contaminated stream is transferred to the first low pressure separator instead of the first intermediate pressure separator. Steps ,
(C) supplying a second co-solvent and purified carbon dioxide to the processing means to form a second contaminated stream in the processing means;
(D) transporting said second contaminated stream in multiphase form to a second intermediate or low pressure separator, said second contaminated stream being a second carbon dioxide rich vapor stream and a second co-solvent; Separating into a second pollutant rich liquid stream , first transporting said second contaminated stream to said second intermediate pressure separator, said batch processing means and said second intermediate pressure separator; Carrying the second contaminated stream to the second low pressure separator instead of the second intermediate pressure separator when a second pressure difference between the first and second pressure values reaches a second predetermined value. Including
The first and second intermediate pressure separators are operated at pressures ranging from 1.38 to 6.21 MPa (200 to 900 psig), and the first and second low pressure separators are operated at atmospheric pressure. How to be.   The method of claim 1, further comprising one or more pressure reducing valves proximate to the processing means upstream of the first and second intermediate or low pressure separators.

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